code: def setup_method(self):
      # G1 is a disconnected graph
      self.G1 = nx.Graph()
      self.G1.add_nodes_from([1, 2, 3])
      # G2 is a cycle graph
      self.G2 = nx.cycle_graph(4)
      # G3 is the triangle graph with one additional edge
      self.G3 = nx.lollipop_graph(3, 1)
  
file_path: networkx/networkx/algorithms/tests/test_efficiency.py
imports: import networkx
label_desc: Use image node_id 1 for calling the TestEfficiency obj's underlying member method code with example usage: obj.setup_method() without return types